Python Startup Script to Terminate Workspace

Hi Mark,

 

 

Try throwing an exception object. For example:

 

-----

 

cursor, connection = None, None

 

try:

 

    # Throw an exception if an unexpected condition has occurred.

 

    if <bad condition>:

 

        raise Exception('message')

 

except Exception as ex:

 

    # Catch the exception and re-throw it to abort the translation.

 

    raise ex

 

finally:

 

    # Clean up resources.

 

    # I think it's better to call the "close()" methods here, like this.

 

    if cursor != None:

 

        cursor.close()

 

    if connection != None:

 

        connection.close()

 

    cursor, connection = None, None

 

-----

 

 

Takashi

Thanks Takashi.

I had tried using raise to throw an exception but thought I'd badly coded when I saw all the red text in the log. Perhaps I expected FME to halt more cleanly than with the exception.

 

 

Updated version:

 

 

import cx_Oracle

 

cursor, connection = None, None

 

 

try:

 

    connection = cx_Oracle.connect('user/pwd@xe')

 

 

    cursor = connection.cursor()

 

    result = cursor.var(cx_Oracle.NUMBER)

 

    cursor.callproc('check_valid_dataset', (123,result))

 

    if result.getvalue() > 0.0:

 

        raise Exception('missing data')

 

 

except cx_Oracle.DatabaseError as e:

 

    error, = e.args

 

    print 'oracle error'

 

    print(error.message)

 

    raise e

 

 

except Exception as e:

 

    print e

 

    raise     

 

    

 

finally:

 

    if cursor != None:

 

        cursor.close()

 

    if connection != None:

 

        connection.close()

 

    

 

Unfortunately, I don't think it can be avoided that the red text appears when an exception has been thrown in startup python process.

 

 

If you can read the source dataset by a SQLExecutor or a FeatureReader, the "clean halt" is possible with this implementation.

 

(1) Define a global variable which indicates the condition in the startup script,

 

(2) Create an initiator feature which has an attribute storing the condition, with a PythonCreator,

 

(3) Check the attribute by a Tester, and halt the translation if the value indicates the bad condition.

 

 

Skeleton:

 

-----

 

# Startup Python Script

 

g_condition = 1 # global variable

 

...

 

if <bad condition>:

 

    g_condition = 0

 

-----

 

# PythonCreator (expose "condition" attribute)

 

import fmeobjects

 

class FeatureCreator(object):

 

    def close(self):

 

        feature = fmeobjects.FMEFeature()

 

        feature.setAttribute('condition', g_condition)

 

        self.pyoutput(feature)

 

-----

 

# Tester

 

Test Clause: condition = 1

 

- Passed => SQLExecutor or FeatureReader (start the translation)

 

- Failed => Terminator or do nothing (halt the translation)

The Tester can also be omitted.

 

-----

 

# PythonCreator

 

import fmeobjects

 

class FeatureCreator(object):

 

    def close(self):

 

        if g_condition == 1:

 

            feature = fmeobjects.FMEFeature()

 

            self.pyoutput(feature)

 

        else:

 

            # log messages if necessary.

 

            pass

As always you supplied a great solution. 

 

Many Thanks!